Classification Of The Lepidoptera

The Lepidoptera are divided into two very unequal groups, to which we have so frequently alluded as ‘Butterflies’ and ‘Moths.’ And, although these two terms are popularly applied in a fairly accurate manner, yet, strange to say, very few persons indeed have any definite knowledge of the differences that entomologists recognise between the two groups.

Every entomologist has his circle of sympathetic and, perhaps, even admiring friends. Consequently, many a little package is sent round to his abode ‘with great care,’ accompanied by a note or a message concerning the fine ‘butterfly I have just caught, and thought you would like to add to your collection.’

The ‘butterflies’ that so frequently reach us through these channels nearly always turn out to be brightly coloured moths, and this naturally gives one the idea that the popular notion as to the classification of the Lepidoptera is based on colour or brilliancy of design, the term ‘butterfly’ being applied to the gayer species, and ‘moth’ to the more dingy members of the race.

There is really some shadow of a reason in this method of nomenclature, for butterflies are usually more brightly clad than moths; but the scientific classification, at least as far as the main divisions and subdivisions are concerned, has nothing whatever to do with colour or design; and we must at once acquaint ourselves with the fact that there are very dingy butterflies, and most beautiful and highly coloured moths.

How shall we account for the fact that the specimens so kindly sent us by our friends are generally moths? Is it because moths are more numerous and more frequently seen? They are certainly more numerous; for, while our butterflies do not number seventy species, the other division contains about two thousand. Yet, in spite of this fact, moths are not generally observed as much as butterflies, for the former are nearly all night-fliers, and the latter always fly by day and rest by night.

Still our question remains unanswered. The reason is this. The captives sent us are seldom caught on the wing. Most of our grown-up friends, even though they admire our own pluck and general carelessness concerning the remarks of the spectators of our entomological antics, would not themselves like to be seen, hat in hand, chasing a butterfly; and the night-flying moths are, of course, less frequently observed. But they often, in the course of their daily employments, meet with a large moth fast asleep in some corner of a dwelling house, workshop, or outhouse. Such moths are easily caught while in the midst of their slumbers, and, as they often make no attempt to fly by day, are as easily transferred to a box suitable for transmission by messenger or by post.

In the above few remarks we have alluded to some features by which the two great groups of the Lepidoptera may be distinguished; but we have already referred to a far more important one in our description of the various forms of antenna. All butterflies-at least all British butterflies-have knobbed or clubbed antenna, while the corresponding organs of all our moths terminate in a sharp point.

This distinction obtains in all British Lepidoptera, and is so far regarded as the most important basis of classification that naturalists have derived from it the two Greek terms that are synonymous with our two popular names-butterflies and moths. The scientific name for the former group is Rhopalocera-a term derived from two Greek words, one signifying a horn, and the other a club, and thus meaning ‘club-horned.’ The corresponding name for moths is Heterocera, derived from the same source, and meaning ‘variously horned.’

But, although we find embodied in these two long and formidable names an unerring mark of distinction between British butterflies and moths, we must not neglect other less important facts which, though less distinctive, are not without interest.

Fig. 37.-A Butterfly at Rest (Large Copper).

Observe a butterfly at rest. Its wings are turned vertically over its back, and brought so closely together that they often touch. In this position the ‘upper’ surfaces of the ‘upper’ wings are completely hidden from view, and the ‘under’ surfaces are exposed on the two sides, except that those of the ‘upper’ pair are partly hidden by the other pair.

Now look at a moth under the same circumstances, and you will generally find the wings lying over its body, which is almost or completely hidden beneath them. As a rule the upper pair together form a triangular figure, and entirely cover the second pair; but in some cases a portion of each of the under wings extends beyond the margin of those above them, and in others the upper pair extend so far forward that nearly the whole of the under wings is exposed behind them.

Fig. 38.-A Moth at Rest (Gothic).

Again, the wings of butterflies are so rigid that they can never be folded; but you will observe that the under wings of moths are generally very thin, soft, and pliant, and are neatly pleated lengthwise when not in use.

Another feature deserving notice is a slight difference to be often observed in the form of the body. The butterfly, which generally has a slender body, has a distinct constriction or waist between the thorax and abdomen. This is not so apparent with moths, and especially with the thick-bodied species.

The Rhopalocera or Butterflies are divided into Families, each of which contains insects that possess certain features in common by which they may all be distinguished from the members of any other family.

2. Pierida.-Containing ten species. These are often known collectively as the ‘Whites,’ but include four butterflies that are distinguished by beautiful shades of yellow and orange.

3. Nymphalida.-This family contains seventeen insects, among them being several splendid species. It includes the Fritillaries and Vanessas.

4. Apaturida.-Of this we have only one representative-the Purple Emperor (Plate V, fig. 1).

5. Satyrida.-Including the ‘Browns’ and ‘Heaths,’ and numbering eleven species.

6. Lycanida.-Including the Hairstreaks, ‘Coppers,’ and ‘Blues,’ in all seventeen species.

7. Erycinida.-Containing only the ‘Duke of Burgundy.’

8. Hesperiida.-This family contains seven British butterflies commonly known as the ‘Skippers.’

Although all the members of the same family resemble each other in certain points of structure, or in their habits, yet we can often find among them a smaller group differing from all the others in one or two minor particulars. Such smaller groups are called Genera.

To make this all quite clear we will take an example.

The Brimstone Butterfly (Plate II, fig. 4) belongs to the second family-Pierida, all the members of which are distinguished from those of the other families by the characteristics mentioned.

But our Brimstone Butterfly possesses another very prominent feature in which it differs from all the other British Pierida, and that is the conspicuous projecting angles of both fore and hind wings. Among the foreign species of the family we are considering there are several that possess these angles; but as there are no others among our own members, the ‘Brimstone’ is placed by itself in the list of British Lepidoptera as the only member of the genus Gonopteryx or ‘angle-winged’ butterflies.

Thus the full relationship of this butterfly to other insects may be shown in the following manner:

The Brimstone Butterfly.

ORDER.–Lepidoptera

Section.–Rhopalocera

Family.–Pierida

Genus.–Gonopteryx

Species.-Rhamni

Now, every butterfly has a Latin or Greek name in addition to that by which it is popularly known. I should have said two Latin or Greek names. The first of these is always the generic name, and the second is the one by which we denote the particular member or species of that genus. Thus, the scientific name of the Brimstone Butterfly is Gonopteryx Rhamni.

‘But,’ the reader may be inclined to ask, ‘why should we not be satisfied with the one popular name only?’ And, ‘If we must have a separate scientific name, could we not find suitable terms among our English words to build up such a name-one that might express the principal characteristics of the insect, and also serve all the purposes of classification?’

Such questions sound very reasonable, and so they are. But the entomologist’s answer is this. We ourselves may get on well without the help of the dead languages, but we have brother naturalists all over the world, speaking a great variety of different languages. We endeavour to help one another-to exchange notes and generally to assist one another in our labours; and this can be greatly facilitated if we all adopt the same system of nomenclature. The educated of most of the great nations generally know something of Latin and Greek, and consequently the adoption of these languages is generally acceptable to all.

This sounds well, but for my own part I believe that if we are to make any branch of natural history a popular study, especially with the young, we must to a certain extent avoid anything that may prove distasteful. There is no doubt whatever that many a youngster has been turned away from the pursuit of the study of nature by the formidable array of almost unpronounceable names that stretch nearly halfway across a page; and those who desire to make such a study pleasant to beginners should be very cautious with the use of these necessary evils. One would think, on glancing over some of the scientific manuals that are written ‘especially for the young,’ that the authors considered our own too mean a language for so exalted a purpose, for in such works we find all or nearly all the popular names by which the schoolboy knows certain creatures he has seen entirely omitted, and the description of a species appended to a long Latin term that conveys no idea whatever to the reader, who is studying the description of a well-known animal or plant and doesn’t know it.

Our plan will be to give the popular names throughout, except in the case of those few species that are not so well known as to have received one; but the scientific names will always be given as well for the benefit of those readers who would like to know them. And the short description of the method of classification just given will enable the more ambitious of my readers to thoroughly understand the table of British butterflies and moths toward the end of the book.

This table includes all the British species of butterflies and of the larger moths; and the arrangement is such as to show clearly the divisions into sections, families, &c. It will therefore be of great value for reference, and as a guide for the arrangement of the specimens in the cabinet.

In the foregoing description of the method of classification butterflies only are mentioned; but the division and arrangement of moths is carried out in just the same manner except that the system is a little more complicated. The number of moths is so large in comparison, that we are able to select from them some very large groups the species of which possess features in common. These groups are termed tribes, and are again divided into families just like the butterflies. Thus the arrangement of moths includes tribes, families, genera and species. We will take an example by way of illustration as we did before, and ask the reader to verify the same by comparison with our table:

Example.-The ‘Common Tiger’ (Plate X, fig. 3).

ORDER.–Lepidoptera

Section.–Heterocera

TRIBE.-Bombyces

Family.–Cheloniida

Genus.–Arctia

Species.-Caia

Scientific Name.-Arctia Caia.

I have already said that the Latin and Greek names of butterflies and moths are not at all necessary to the young entomologist. It is quite possible to be well acquainted with the natural history of these creatures, and to derive all the pleasure and benefits that the study of them can afford without the knowledge of such names; but most entomologists go in for them, often to the entire exclusion of the popular English terms.

There are those who consider themselves (or would have us consider them) expert entomologists because they have the power to vomit forth a long list of scientific names of butterflies and moths which (to them) have no meaning whatever; and it is astonishing that we meet with so many youngsters who can rattle away such terms, and, at the same time, are totally ignorant of the real nature of the creatures they name.

If you wish to be a naturalist in the true sense of the term, study your specimens, and take but little pains to commit their hard names to memory; and you will then find that the latter will gradually become your own property without any special effort on your part. Your continued reference to illustrated works and museum collections will bring them to you almost unconsciously, and you will generally find your entomological vocabulary extending as rapidly as your cabinet becomes filled.

Again, with regard to the meanings of the scientific terms, don’t trouble much about them. It unfortunately happens that in a very large number of cases these names are ill chosen, and do not in any way refer to the distinguishing characteristics of the species to which they are applied. You will observe, too, if you look at the table, that many insects have two scientific names applied to the species, one being placed in brackets after the other. In such cases both these names are in common use, having both been applied by independent authorities, and the insertion of the two will prove an assistance at times.

It is a common practice with entomologists, in their communications, to use only the second or specific name of insects. Thus, they would speak of the Brimstone Butterfly as Rhamni, and not Gonopteryx Rhamni. When writing a communication, however, they very commonly place in front of the specific name the initial letter of the first or generic name. Thus the full title of the butterfly just mentioned would be abbreviated to G. Rhamni.

Having said so much concerning the principles of classification and nomenclature, we will pass on to the practical portion of the entomologist’s work.